Low Boost on BNR S3

I recently installed a BNR S3 that I picked up from a member here, a JBR 3" intake, a Grimmspeed 3 port, 3 Bar Map with bitwise adapter, a DM OCC, and hpfp internals on my MS6. I'm getting tuned by a reputable e-tuner here. The thing will not make more than 9 psi of boost.

Everyone would normaly say boost leak. I've tried tightening all of my couplers. I made a boost leak tester and found that my hybrid bov as well as the cold side coupler were leaking. So I put the stock bpv back on and fixed the coupler leak. Still 9 psi. The car runs great, no weirdness, and seems to pull fine for the amount of boost it's making.

My key on engine off boost is -2 psi. I've tried two different sets of numbers for the map scalars with no change.

When boost leak testing, the wastegate didn't crack until 14ish psi, as indicated by monitoring with versatune. I bypassed the ebcs for now, just to rule it out, with a hose running straight from the compressor housing to the wastegate, and with the nipple on the intake blocked off.

I've attached a couple of logs that were taken with the ebcs still connected.

I'm running out of ideas, so I need yours. I'm a noob when it comes to this, maybe I'm missing something.

 

My first question here is have you chatted to your tuner? What is the tune commanding be for boost because as a first map 9 psi could be reasonable. Although the -2psi at idle is rather low. Now cracks in any pipes or couplers? How's your ebc connected?

 

Hopefully it is a simple fix, ran on my car like a champ!

 

Something seems wrong with your map sensor as it should read pretty close to 0 when the engine is off. Do you have an aftermarket map sensor that maybe your tuner doesn't know about?

 

You know, when my 3BAR took a shit, it did the Exact same thing. Being self tuned I changed my settings, checked my math, and I could not for the life of me get the MAP to read correctly. I ended up changing the sensor and the problem was fixed.

If You need a MAP sensor? I'll throw one on my For Sale page, I think I may have one in my box of parts.


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My tuner and I have been discussing it. WGDC is zero'd out currently, but boost isn't even making it to spring pressure. EBCS was connected according to grimmspeeds instructions, and is currently bypassed.

Map sensor is brand new from bitwise, and my tuner knows about it.

The map sensor is brand new from bitwise, so if it is bad, I'll probably take it up with them. When yours went bad, did it affect your ability to build boost at all or did it just affect your readings?
[doublepost=1487973883][/doublepost]Something that I did forget to mention is that I reused exhaust manifold gasket when I pulled the turbo, since I ended up pulling the manifold as well.

Also, when I replaced the pcv valve, and I reused the intake manifold gasket, so that could be a problem.

 

I could drive the car just fine. My negative boost pressure seemed register correctly at idle and light throttle, so I didnt worry tto much. I just did not go WOT until I got it fixed. Make sure to talk with your tuner first to make sure its not a tuning error before changing it out the MAP. I was also running a sensor and cable from them, IIRC. Do you happen to know the part number on the senor?

 

I forgot to take a picture of it, but I'm pretty sure it was the 0 281 002 845, I know for sure the last three (of the part number) were 845.

 

Interesting development. I swapped the stock map sensor back in, changing back to the stock map numbers in the tune as well. And now it reads -0.1 psi with the engine off, and peak boost of 13 psi. So I very well could be hitting spring pressure, and the map sensor was just reporting low.

 

Interesting update. I got a new 3 Bar from JBR, installed it, reflashed the tune, and it's back to -2 psi engine off, peak of 9 psi. I trust my factory map sensor, it always read correctly with my k04, and I doubt I got two bad map sensors in a row. So 13 psi should be the number I'm actually hitting. @Littleloogy Did you change your adapter harness when you changed map sensors? I'm beginning to wonder if the adapter harness is wired improperly.

 

Did you change the map scaling values when you changed the sensor? The ecu will not get the right values if you dont

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Yes I reflashed the tune my tuner originally sent me, which has the scalars for the bosch 3 Bar (845).
Those numbers (for Versatune) are:
8.35 - (additive),
65.78 - (base multiplier),
1 - (second multiplier).

 

Was going to offer this as a next possible point of failure. I'm assuming you only tried a new MAP sensor from JBR and are still using the original PNP harness he sent you? That could very well be where the fault lies if your stock MAP is reading fine but two different aftermarket MAPs are off.

 

Or the stock one is off and the other two are correct :O

 

I'm probably going to try pulling the harness and check it for high resistance. I doubt the sensor would work at all with the wrong pin out, but I'll check that too.

 

So I was doing a bit of reading this morning, and someone had mentioned the drop down menu for map sensors in versatune.....

Apparently, versatune has a setting on one of the dashboard parameters, specifically intake manifold absolute pressure, that adjusts how it scales the map data while monitoring and logging. This is just for the dashboard, it has nothing to do with the tune. Here's a picture.



Adjusting the setting on this parameter changes not only how it displays information, but also how the Boost Pressure parameter displays as well. I had no clue this was here, because we weren't using this parameter for logging, we were using boost pressure, which doesn't have this setting. As soon as I changed it from stock to 3 bar, it went from reading -2.0 psi with the engine off to 0.1 psi. And peak boost went from 9 psi to 13.9 psi.

So there's probably nothing wrong with my map sensor, map sensor adapter, or my tune. Bitwise did not send me a bad map sensor or harness. Flashing the next revision of my tune tomorrow, so we'll see if it responds to some wgdc.

I could have saved myself 3 weeks of troubleshooting with this little tidbit of knowledge. I wish it wasn't buried into a parameter, and was a universal function on the main settings instead. Such is the way it goes I guess.